Given the following code, find the compile error. public class Test{
public static void main(String[] args){
m(new GraduateStudent());
m(new Student());
m(new Person());
m(new Object());
}
public static void m(Person x){
System. out. println(x. toString());
}
}
class GraduateStudent extends Student {
public String toString(){ return "GraduateStudent";}
}
class Student extends Person{
public String toString(){ return "Student";}
}
class Person extends Object{
public String toString(){ return "Person";}
}
a. m(new Object()) causes an error
b. m(new Person()) causes an error
c. m(new Student()) causes an error
d. m(new GraduateStudent()) causes an error